Spend time around the center of town at the local plaza and see the murals besides the Catholic Church.
San Sebastian has lots to see and enjoy. One of my favorites is Gozalandia Falls. You can just take your family, significant other or just hang with your friends for the day and enjoy all that mother nature has for you.
Nice park with rock climbing, hiking, zip line, tennis and volleyball courts, all on a high hilltop with great views of the surrounding area. Walking trails with suspension bridge.